This question is to simple. So the answer can be yes and no and both are correct.

I use two GTX980 non TI in sli, too. My Screens (3) are 1080p@144Hz with a G-Sync module. My memory doesn't hit the 4GB and power is enough for playing Warthunder, Borderlands (since 2), CS:GO and Witcher III: Wild Hunt.

So as long nobody know, which screens you use and what you play, nobody can't answer your question.